Master clock



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MASTER CLOCK Filed May 24, 1943 5 Sheets-Sheet 2 IN VENTOR.

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5 Sheets-Sheet 5 Filed May 24, 1943 Wy v INVENTOR.

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' MASTER CLOCK Filed May 24, 1945 5 Slieets-Sheet 4 IN VENTI'OR.

M. L. HAMLIN MASTER CLOCK Sept. 13, 1949.

5 Sheets-Sheet 5 Filed May 24, 1943 INVENTOR.

Patented Sept. 13, 1949 UNITED STATES PATE T-orifice MASTER CLOCKMarlton Lovell Hamlin, Lynbrook, N. Y. Application May 24, 1943, SerialNo. 488,189

16 Claims.

This invention relates to a clock comprising an isochronouslyoscillating member which is undamped at the ends of its excursions andis maintained byshort, sharp, banked impulses at substantially the midpoints of its excursions, and a counting mechanism which counts insuitable units the number of excursions of the oscillating member andwhose action is controlled by said impulses independently of saidoscillating member. More particularly the invention relates to apendulum clock in which short, sharp, banked impulses are applied to thependulum bob in phase with its swings, the pendulum being entirely freeat the ends of its swings, and in which no energy for operating dialworks or other counting mechanism is taken from or reacts on thependulum.

It is one object of this invention to provide a commercial precisionclock requiring a minimum of precision operations in its construction.

It is another object of this invention to provide a commercial precisionclock containing few and simple moving parts.

It is another object of this invention to provide a clock whosetimekeeping shall be in a high degree independent of the mechanicalcondition and state of lubrication of its works.

It is another object of this invention to provide a commercial precisionclock to serve as a master clock or program clock or clock for thecontrol of tower clocks, from which any desired number of signals orcontrol impulses at desired intervals may be taken off without in anydegree affecting the rate of the clock.

It is another object of this invention to provide a clock in which a.pendulum or other isochronously oscillating system receives a constantimpulse of very short duration substantially at the mid point of itsexcursions and is free of interference at the ends of its excursions.

Other advantages will appear in the following description to thoseskilled in the art.

Hitherto it has generally been considered desirable in order to avoiddisturbing vibrations to apply impulse to a pendulum or other oscillatinmember used for timekeeping in the form of a gentle pressure ofsubstantial duration, the pressure increasing gradually to a maximum andgradually decreasing during the impulse period. In some forms ofescapement, e. g., in the recoil and Graham dead-beat anchor escapementsand in the Grimthorpe gravity escapement, the impulse members act on orare acted on by the pendulum during all or the greater part of itsswing. In others, e. g., in the Synchronome escapement, the impulse isconfined to a fraction,

2 but a substantial fraction of the total swing. In all cases, however,the impulse involves a certain amount of rubbing or rolling frictionbetween the pendulum and other parts of the mechanism for a sensiblefraction of the pendulum swing.

I have found that this friction and relatively prolonged interferencewith the swing of the pendulum may be avoided without introducingundesirable distortions or vibrations of the pendulum by applying theimpulse in the form of a light, practically instantaneous tap to anadequately heavy pendulum bob at or near the mid point of its swing. Ihave further found that by banking or limiting the fall of the impulsemember at a fixed point I may make the impulse selfcompensating forminor variations in its velocity or force,.thereby maintaining theamplitude of the pendulum substantially constant.

In one embodiment of my invention an impulse is imparted to the bob of aseconds pendulum at every complete swing (i. e., every two seconds) atthe center of its swing by a gravityor springloaded impulse member whichis periodically released by a trigger pull on the pendulum acting on a,light trigger mounted on a detent which engages the impulse member. Ihave found it practical to have this release occur not more than 10'-15'of are from the center point of the swing when the half swing of thependulum amounts to approximately 1 to 1 30' of arc; the duration of therelease action is extremely short; the rest of the swing is free ofinterference except for the nearly instantaneous impulse tap at thecenter. This interference is not only small and of short duration, butsubstantially constant in phase and amount. These conditions, viz.,minimum constant interference limited to the center portion of thependulum swing, make for precise timekeeping. Furthermore since theimpulse is applied to the bob rather than to the rod, it produces noperceptible distortion of the rod or undesirable vibration.

Several preferred embodiments of my invention are illustrateddiagrammatically in the accompanying figures and are described below.but the invention is not intended to be limited thereby.

Figure 1 illustrates the pendulum unit of one embodiment of my inventionas seen from the front.

Figure 2 is a section on the line 2-2 of Figure 9..

Figure 3 is a front view of certain details of the impulse and resetmechanism of Figure 1.

Figure 4 is a sectional view on line 4-4 (Figure 5) of a portion of themechanism shown in Figures 3 and 5.

Figure is a front view of the impulse-member mounting.

Figure 615 a plan view of the electromagnet pole pieces and armatureshown in elevation in Figure 3.

Figure 7 illustrates the back and Figure 8 the front of one form ofcounting mechanism.

Figure 9 is an elevation of a modified electric maintenance mechanism.

Figure 10 illustrates on method of taking period signals or impulsesfrom a clock embodying this invention.

Figure 11 is a front elevation of a gravityor spring-operatedmaintenance device embodying my invention.

Figure 12 is a section on line I2-I2 of Figure 11 and indicatesdiagrammatically it relation to and dial works.

Figure 13 is an elevation and Figure 14 a plan in simplifieddiagrammatic form of a modified electric maintenance and countingsystem.

In the drawings the heavy line 1 represents the outline of a case whichmay be hung on a wall by hanger 2 screwed to an angle-iron bracket 3inside the case. Two pieces of angle iron 4 are welded to bracket 3 toform a support for threaded stud 5 which turns freely in threaded holesin supports 4. A hook 8, firmly secured to stud I by nuts I, carriesjams 8 between which thin steel suspension springs 9 are gripped byscrews passing through holes in the springs. A bar l0 also carries jamssimilarly gripping the lower ends of springs 9.

Pendulum rod II, made of a low-expansion nickel-steel alloy. is threadedinto bar I0 and locked by nut I2. Bob I3 has a hole passing through andperpendicular to its axis through which the lower threaded end of rod II passes with a sliding fit. The bob is supported on the rod by ratingnut I4, locked b nut I5. Number I0 and I1 indicate small shelves fixedon rod I I, on which rating weights may be placed. A pointer II on thelower end of the rod and scale I8 fixed to case indicate amplitude ofpendulum swings.

A metal panel 20 carries the maintenance gear for keeping the pendulumswinging. At its righthand end it rests on fixed stud 2| against whichit is held by spring 22. At its heavier left-hand end it is supported byadjusting nut 23 bearing on bracket 24' fixed to panel 20; nut 23 isthreaded on low-expansion-alloy rod 24 which at its lower end passesthrough a hole in bracket 24' and at its upper end is fixed in bracket3. Fixed studs 25 carry spring clips 26 which keep panel 20 in verticalalinement while permitting vertical adjustment by nut 23, and horizontaladjustment by means of jaws 21 and 28 engaging stud 2| and independentlypivoted on stud 29 fixed in panel 20. Jaw 21 is pressed against stud 2|by tension spring 30, while jaw 28 is pressed against the other side ofstud 2| by adjusting screw 3| threaded through a stud fixed in panel 20.

The impulse and reset gear i indicated in general at 40 in Figure 1 andshown in greater detail in Figures 3-6.

An impulse member 4|, pivoted at 42 on a twopart brass arbor, carriesdetent arm 43 engaging detent 44. On one part of arbor 42 is fixed theinner end of spring 45, the outer end of which is fixed to stud 46adjustably mounted by an arm 47 on panel 20. Member 4| also carries cam48 on its upper portion. Member 4| is adapted to engage anvil 4| carriedby bob I3 when 4| is in its released p sition, but is high enough in itsas the pendulum member 4| by screw II and is thereby grounded to panel20 through spring 48 and arm 41 and their respective mountings which areof brass. Lead 84, which is still! enough to be self-supporting iselectrically connected to the outer end of flexible spiral conductor 80,which is advantageously a ribbon of brass shim stock 0.001 inch thick.The spiral conductor at its inner end is connected with wire mount I!carried by brass plate 60 connected with lead I08.

Posts 60 mounted in panel 20 carry outer brass plate 63 in whichoutboard pivot 42 is mounted by means oi. adjustable bearing 04 threadedinto the plane and locked by nut 52.

Brass plate 88 is mounted on Bakelite block 50 which is mounted on plate63. Lead I03 is thus insulated from panel 20 which serves as ground.Part of outer plate 03 is omitted in Figure 3 for greater clarity.

Adjustable banking screw 6| threaded into stud 82 mounted on panel 20limits the movement of impulse member 4| by contact with detent arm 42.

The impulse-reset mechanism comprises electromagnet I0 with coil 'II andpole pieces 12 adapted to attract armature 13. The latter is carried ona rocking member pivoted at 74 on an arbor supported between panel 20and a front plante 80. This member consists of a central brass block I5and four perpendicular arms 10 fixed in the block; three or these armscarry ad- Justable balancing and inertia weights I1. The lower arm I6also carries a small stud I8 screwed into the arm perpendicular to theplane of the diagram and adapted to engage cam 48 when impulse member 4|is in its released position. Adjustable banking pins BI and I2 limit therotation of the rocking member.

Electrical energy to operate the clock is provided by storage batteryI00 (Figure 1), connected to the clock by leads IOI and I02. Lead I03connects lead I0| with mercury switch 50; lead I04 is connected withmagnet coil 'II- and with panel 20 to which the switch is grounded bylead 53, and thus connects the switch with magnet coil II A condenserI05 to suppress sparking in the switch 50 bridge leads I03 and I04. LeadI00 from magnet coil connects with lead I02 through variable resistancI01.

Leads I08 and I0! connect leads I04 and I02, the latter through variableresistance IIO, with the counting mechanism of the clock, i. e., thedial works, described below and shown in Figures 7 and 8,

Impulse member 4| is maintained in the position shown by contact of arm43 with detent 44. The latter is pivoted at 85 and the upper arm held asshown against banking pin by hair spring 81. A small face plate 80supports the outer pivot and is carried by back plate 88' which supportsthe inner pivot. Plate 88' is adjustably mounted on panel 20 by screw89.

The lower portion .of detent 44 carries trigger 80 pivoted on the detentat 9|. An upper projection of the trigger engages lower radial arm ofthe detent. The trigger is thus free to pivot in a clockwise direction,but on being moved In a counterclockwise direction it carries detent 44aasaoar' with it. The trigger normally hangs in a vertical position asshown.

Horizontal rod 92 is adjustably mounted on rod Hand carries adjustablymounted trigger pull 93.

The various adjustments having been properly made, operation of theisochronous or pendulum unit of the clock is as follows:

Assume the pendulum set in motion manually and swinging from its centerposition to the left. Trigger pull 93 pushes aside trigger 90 and letsit fall without disturbing detent 44; the pendulum completes itsexcursion to the left undisturbed. On its return trigger pull 03 againengages trigger and moves it to the right. This time, however, thetrigger carries the detent 44 with it by virtue of the engagement of theupper projection of the trigger with the lower radial arm of the detent,until the trigger falls of! the trigger pull and the detent is againforced back lightly against banking pin 86 by spring 81.

This movement of the detent releases arm 43, so that impulse member 4|falls towards anvil 4| urged by spring 45, and is stopped at the end ofits motion by contact of arm 43 with banking screw 6|.

If pendulum is swinging with correct amplitude, impulse arm 4| strikesanvil 4| hor'zontally at center of pendulum swing, and at the same timearm 43 strikes banking screw 6|, If excursion of pendulum is too wide,its velocity at center of swing will be greater, so that it will havepassed center point before impulse arm is arrested by banking screw;consequently arm 4| will not strike anvil 4| before pendulum passescenter point and arm is arrested by banking screw. The pendulum thusreceives no impulse and its amplitude is lessened. On the other hand ifthe excursions are too small, velocity will be less, and arm 4| willstrike anvil 4| before pendulum passes center point. The spring 45 isadjusted to furnish slightly more impulse than is needed for maintainingthe oscillations of the pendulum; consequently the ampltude of its swingwill increase until the excess impulse energy is absorbed by pin 6|.Furthermore when the bob is moving faster, if struck by impulse arm itwill absorb less energy. and when moving slower more energy from im ulsearm which always moves at the same rate.

As will be seen from the above, the pendulum w ll take just sufficientenergy from impulse arm 4| to ma ntain its swings at substantiallyconstant amplitude. or will average out small variations and thus avoidany cumulative error.

As impulse arm 4| falls and arm 43 swin s towards the hor zontal,mercury drop 5| rolls against electrodes 52 and closes the circuit toelectromagnet co l 1| from battery I00 by leads |0|, I03. 54, 53. groundthrough panel, leads I04 and I06 through resistance I01 and lead I02 andauxiliary connections described.

On bein energized. magnet 10 sharply attracts armature 13. This resultsin stud 18 being thrown smartly against cam 48 with sufficient force, byvirtue of the inertia of weights 11, to reset arm 43 on detent 44 (whichafter being pushed aside is restored to locking position by spring 81),while drop 5| rolls away from electrodes 52, thus opening the circuit.Lower rocker arm 16 falls back by gravity against banking pin 82 owingto the adjusted balance of weights 11, and the cycle is ready to berepeated.

It will be seen that the impulse supplied to the pendulum issubstantially constant and entirely independent of current strengthprovided only that there is sufiicient current to operate. The impulseassembly (4|, 43, 48, 50). and the detent assembly (44, 00) are o'fverylight construction and springs 45 and 81 ar relatively weak, so thatfriction on pivots 42 an ,85 and between trigger pull 03 and trigger 90is very small. Little change takes place in the operation of these unitsover extended periods of time. The impulse is independent of themechanical condition and state of lubrication of most of the mechanism,i. e., of the reset mechanism above described and the counting mechanismdescribed below, the only requirement being that they be in suflicientlygood condition to operate.

The impulse arm may be gravity-loaded by appropriate weighting, andspring 45 may then be dispensed with.

For the most refined work pivots 42 and 85 may be mounted in jeweledbearings, trigger and/or trigger pull 03 may be jewelled and springs 45and 81 may be made of Elinvar or similar alloy of lowtemperature-stiffness coefficient.

In the counting mechanism (Figures 7 and 8) three hands 20l, 202 and 203show respectively hours, minutes and seconds. They are of the jump type,i. e., the hour hand moves only at the end of each hour and then movesforward an hour interval on the dial, the minute hand moves similarlyeach minute and the'second hand each second. These hands are carried onarbors 20|', 202 and 203' pivoted in plate 204 and in bridge platesomitted from the drawings for clarity.

Each arbor carries fixed to it a toothed wheel,

respectively 205, 206 and 201. Wheel 205 has 24 teeth, and wheels 206and 201 60 teeth each. On each of the two latter wheels is fixed aspiral cam 208 and 209.

A half-second compound pendulum 2|0 with upper and lower bobs is mountedon pivoted arbor 2 which carries fixed to it armature 2 I2. When thependulum swings the armature swings alternately into line with and awayfrom poles 2|3 of an electromagnet (shown partially cut away in thedrawing) which is mounted to the rear of wheel 201 by means of postsscrewed into plate 2 4.

A gathering pawl 2|4 is pivoted on armature 2|2. Its lo er end is adaped to en a e the teeth of wheel 201. Pivoted at 2 IS on pawl 2|4 are twolinks 2" and 2|8. Slots in the outer ends of the links embrace fixedpins 2|9 and 220 so that the links are capable of a limited sliding androtational motion on the pins. The lengths of the links and thepositions of the pins are such that they permit pawl 2|4 to engage andgather one and only one tooth of wheel 201 at each com lete oscillationof pendulum 2|0 (when it oscillates through a sufficient angle).regardless of how great the amplitude is beyond the required minimum.

An electric impulse is transmitted once every two seconds by leads I08and I09 to the coil 2|3 (shown partly cut away) of the electric magnetprovided with pole pieces 2| 3, the periodicity being preciselycontrolled by the above described movements of the mercury switch 50,which is controlled in turn by the swings of pendulum ll, l3.

The bobs of pendulum 2|0 are adiusted to give it an approximate/z-SGCOIld rate (one complete swing each second) accordingly theelectric impulses arriving at exactly two-second intervals energize polepieces 2|3 at exact two-second intervals, thereby setting in oscillationthe compound pendulum 2|0 and maintaining it in am- 7 chronism with butat twice the rate of the main pendulum ll, [3. The inertia of the bobsof pendulum 2!0 is suflicient to keep it swinging eight or ten timeseven if the electric impulses should be temporarily discontinued.

Since the /2-second pendulum makes a complete swing each second, theattached gathering pawl 2|4 advances wheel 201 one tooth or /60revolution each second, and accordingly associated hand 203 indicatesseconds on its dial (Figure 8). Spring-tensioned pawl 22!, bearing onthe teeth of wheel 201 prevents overrunning and retrograde movements ofthe wheel.

The left end of rocker arm 225 (viewing Figure 7) pivoted at 226 ispressed lightly against cam 209 by spring 221, which draws up the leftend of rocker arm 228 against stud 229 on the right end of rocker arm225. Rocker arm 228 is pivoted at 230; at its right end it carriesspringtensioned pawl 23! which engages teeth of the minute wheel 206; italso carries fixed stop 232 which engages the teeth of wheel 205 andprevents overrunning of the wheel on completion of a downward stroke ofthis end of the rocker arm.

As wheel 201 is rotated, cam 209 raises the left end of rocker arm 225and depresses its right end. Stud 229 accordingly depresses the left endand raises the right end of rocker arm 228. As wheel 201 rotates hand203 to the 60-second point, arm 225 falls off the end of cam 208, andspring 221 rocks arm 228, depressing pawl 23! and advancing minute wheel206. The lift of cam 209 and the lengths of arms 225 and 228 are sochosen that pawl 23! gathers one and only one tooth of wheel 206 in eachcycle of operation of the rocker arms. Accordingly hand 202 is advancedone minute on its dial each time hand 203 reaches the 60-second mark.Spring-tensioned pawl 233 bearing on the teeth of wheel 206 preventsretrograde movement of the wheel.

Similarly the rotation of wheel 206 and spiral cam 206 advances wheel205 by means of rocker arms 235 and 238, pivoted at 236 and 231, tensionspring 239 and spring-tensloned pawl 240 engaging the teeth of hourwheel 205. In this case, however, the lift of cam 208 and the lengths ofthe arms 235 and 238 are so chosen as to advance wheel 205 &4 revolutioneach cycle. Accordingly associated hand indicates hours on its 24-hour,

dial. Spring-tensioned pawl 24! bearing on the teeth of wheel 205prevents overrunning and retrograde movement of the wheel.

The embodiment illustrated in Figure 9 is in general similar to theembodiment illustrated in Figures 3 and 6, but differs from the latterchiefly in that the reset lever (a) is balanced to reset the impulsemember by gravity after each impulse, (b) is released to do this by thecontact of a corn on the impulse member with a detent lever, and (c) isrestored to its raised position by an eiectromagnet. The magnet iscontrolled by a mercury switch operated by a forked arm on an extensionof the reset lever. Instead of a mercury switch various types ofmechanical switch can be used.

This form of the invention has more moving parts than that shown inFigure 3 but has the advantage that the impulse member, having nomercury switch and thus being considerably lighter in weight, acquiresgreater angular acceleration from a comparatively weak spring. Thislessens the interval between trigger pull and impulse and brings thetrigger pull proportionately nearer the center swing.

In the drawing for the sake of simplicity and clarity certain detailsidentical with those in Figure 3 have been omitted. Identical parts inFigures 3 and 9 are indicated by identical reference characters and havethe same functions in both embodiments.

Construction and operation of this escapement are as follows: Triggerpull 93, trigger and detent 44 function as in Figure 3. Impulse memher340 differs from impulse member of Figure 3 in carrying no switch and inhaving a cam 348 differently located from cam 48; it is pivoted at 42between plate 363, mounted on studs 60 and metal panel 20. Detent lever34! is pivoted at 342 between plate 343 and panel 20; its lower arm isheavier than its upper and consequently it normally rests on stop 344.At its lower end lever 34! carries a short perpendicular pin 345projecting into the plane of cam 348. At its upper end lever 34! engagesprojection 313 on body 315 of reset lever.

The reset lever, pivoted at 14, is weighted by weight 311 on arm 16 sothat, when released, it tends to rotate clockwise till stopped bybanking pin 382.

The lower portion of body 315 carries curved arm 310 in a plane parallelto panel 20 but on the opposite side of impulse member 340 from thepanel. At its lower end it carries pin 319 extending perpendicularlytowards pane into the plane of impulse member 340.

At the upper portion of body 315 are affixed armature 13 (constructedand functioning as in Figure 3) 'and extension arm 316 with fork 318 atits upper end adjusted to operate mercury switch 350 as described below.

Switch 350 contains a drop of mercury 35! adapted to close the circuitbetween two electrodes 352 when the electrode end of the switch isdepressed. The switch is carried in a clip pivoted at 355 between panel20 and a small plate 356; the latter carries brackets with limit screwspoint of the pendulum 351 threaded in them to adjustably control extentof movement of the switch. Rigidly fixed to the switch clip is arm 353carrying perpendicularly fixed pin 354 positioned to be engaged by armsof fork 318. The electrodes 352 are respectively connected to extremelyflexible leads 303 and 304, e. g., helical ribbons of 0.001 inch brassshim stock. Lead 304 is grounded to panel 20, to which lead !04 isconnected, while lead 303 is connected to lead I03 at post I03 insulatedfrom panel 20.

When arm 43 is released and arm 4! delivers its impulse to anvil 4! (asdescribed in connection with Figure 3), cam 348 strikes pin 345 thusrotating lever 34! slightly clockwise and disengag ing its upper endfrom projection 319 On body of reset lever. This permits the reset leverto rotate clockwise on its axis 14 under influence of weight 311,thereby bringing pin 319 into contact with the upper part of impulse arm4!. This forces entire impulse member 340 to rotate clockwise and resetsarm 43 on detent 44 as described in connection with Figure 3.Simultaneously upper arm 316 moves to the right, bringing the leftfinger of fork 318 into contact with pin 354 on arm 353 of switch clipand rotating switch 350 counterclockwise sufficiently to cause mercurydrop to roll to electrode end of switch. Reset lever comes to rest whenarm 16 strikes banking pin 382.

Contact of mercury with the electrodes closes circuit with battery Ithrough electromagnet coil II by means of leads IOI, I03, 303, 304, I04,I00, I02 and auxiliary connections described. Energizing of magnet I0 inthis way attracts armature I3, thus rotating reset levercounterclockwise on its axis I4 until projection has risen past top ofdetent lever 34I. Banking pin 38I limits rotation in this direction bycontact with arm I5. Simultaneously the right arm of fork 318 strikespin 354, rotating switch 350 clockwise to position shown in the figure,thereby opening circuit to magnet coil II. The reset lever being freedof the attraction of the magnet, falls back slightly till held bycontact of projection 319 on end of detent lever 3, as shown in Figure9.

The distances, inertias and magnetic attraction are made such that thetime required for this cycle of operations is only a small fraction ofthat needed for a complete swing of pendulum II, I3. Accordingly theimpulse mechanism is in postion to repeat the cycle at each swing of thependulum, and oscillations of the pendulum are thereby maintained.

A counting mechanism or dial works of desired design is "connected inparallel with 0011 'II by leads I08 and I09 as illustrated in Figure 1,and thereby indicates time as previously'described. The dial works mayadvantageously have the form shown in Figures 7 and 8.

Alternatively by suitable changes in magnet coils and resistances inwell known ways, the counting mechanism may be connected in series withcoil II.

When it is desired to use the clock of this invention for transmittingperiodic signals, a separate battery or other source of electric currentI000 (Figure 10) may be provided, connected by one lead with a suitablesignal or electrical impulse transmitter IO0I. Arbors such as MI, 202'and 203 of the dial works, electrically insulated from each other, carryrespectively contact arms I20I, I202 and I203, adapted on rotation ofthe arbors to make contact with adjustably fixed spring contact armsI2II, I2I2 and I2I3. Transmitter IO0I is connected by a lead and wipingcontact with arbor 20I. Spring contact arm I2 is similarly connectedwith arbor 202 and spring arm I2I2 with arbor 203. Spring arm I2I3 isconnected by the other battery lead with battery I000. The threecontacts, the battery and the transmitter are thus connected in series.As the contact arms mounted on the arbors 20I' 202' and 203' rotate inthe direction of the arrows they periodically make contact with thespring arms I2II, I2I2 and I2I3, arm I20I once in 24 hours for 1 hour,arm I202 once an hour for 1 minute, and arm I203 once a minute for 1second. Since all contacts must be closed to transmit a signal, thearrangement described will transmit a signal of l seconds duration onceevery 24 hours. In the diagram this will occur at OO OO OO to 00 00 0lBy suitably altering the position of fixed arms I2II, I2I2 and I2I3angularly around the respective arbors, the time at which the signaloccurs may be altered at will in one-second steps.

If only a momentary signal is desired arm I2 I3 may be adjusted so thatarm I203 contacts it only between two second stations, e. g., between 14and 15 seconds.

Signals at other intervals may be transmitted by similar arrangements inways readily understood by those skilled in the art. For example, byshort-circuitin the contact on the 24-hour arbor 20l', the arrangementshown will transmit one-second signals once an hour; by doing this andalso providing four spring contact arms electrically connected inparallel and spaced apart around hour arbor 202, one-second signals willbe given every 15 seconds. An almost unlimited variety of signals, bothas to duration and timing, is thus possible by using suitableconnections and contacts.

The signals or electrical impulses thus lsent may be used to operatelights or bells, to control process cycles, actuate or controlmachinery, tower clocks, secondary clocks and the like by suitablerelays, amplifiers or other devices well known to the art.

The important feature that these various methods and means of signaltransmission have in common is that, in contradistinction to manypreviously suggested signaling methods, those described have no effecton the running rate of the clock. This is because, as pointed out above,the operation of the dial works or counting mechanism does not in anyway react on the operation of the pendulum, regardless of the particulartype of counting mechanism used or the particular form or motive powerchosen within the scope of my invention.

Figure 11, a cut-away front view, and Figure 12, a side view partly insection, represent another embodiment of my invention in which apendulum is maintained in oscillation and its swings counted bymechanical instead of electrical means.

In these figures II is the pendulum rod, I3 the bob, and H the anvil; 20is the panel supporting the maintaining gear 400. Trigger-pull 93 isadiustably fixed on rod 92 mounted adjustably on rod I I. Detent 44pivoted at 85, banking pin 86, spring 81 and trigger 90 pivoted ondetent 44 at 9I function as in the first described embodiment.

A weighted impulse member 0 is mounted on arbor 420 pivoted between faceplate 40I and back plate 402. Face plate 40I, of the same size and shapeas back plate 402, is omitted in Figure 11 for clarity. Detent arm 430is formed integral with member 4I0, as is reset arm 480. In the positionshown detent arm 430 engages detent 44, holding member 0 in a raisedposition above the path of swing of anvil 4'I and bob I3.

An escape wheel IE0 is mounted on arbor I40 pivoted between plates 40Iand 402. The latter are held in spaced relationship to each other andalso mounted on panel 20 by posts 403. Escape wheel I60 carries threeradial teeth I6I and three rearwardly extending pins 162. On rotation ofthe escape wheel the teeth in turn engage one end of detent 500 pivotedat 50I; the other and heavier end of the detent carries adjusting screwI00 adapted to engage detent arm 430 when the latter is released bydetent 44. Banking pins 502 and 503 limit the movement of detent 500.Pins 162 are adapted to engage arm 480 when detent arm is released andwhen escape wheel revolves.

Arbor also carries fixed on it bevel gear 80I meshing with bevel gear802 fixed on vertical shaft 803; the latter is rotatably mounted inbrackets 804. Shaft 803 is connected, as by a universal joint, withshaft 806. The latter is connected with any suitable type ofconventional clockwork, dial, hands, etc., indicated at 806,, to whichpower is continuously applied by spring, weight or other means. Thedirection of rotation impressed on the clockwork by this means is suchas to force escape wheel 160, as seen in Figure 11, in acounterclockwise direction. The gear ratios are such that the hands oithe clockwork are advanced six seconds for each full revolution ofescape wheel 160. The clockwork and its connections are of conventionaltype well understood by those skilled in the art and require no furtherdescription.

The operation of this mechanism is as follows: When the pendulum swingsto the left (viewing Figure 11) after being set manually in motion,trigger pull 93 raises and drops trigger 90 with out moving detent ll,as described in connection with Figure 3. On the return swing thetrigger pull momentarily pulls aside trigger 80 and detent 44, releasingdetent arm 430. This permits weighted impulse arm to fall, strikinganvil 4i and imparting an impulse to bob i3, the timing being soadjusted that this occurs at the center of the swing. The weight on arm0 is chosen so as to furnish slightly more energy on striking anvil llthan is required to maintain the oscillations of the pendulum. The fallof member 0 causes arm 430 to rise and strike adjusting screw 109,raising it and depressing opposite end of detent m. This action of thedetent releases escape wheel 160, which rotates counterclockwise, beingpropelled by the force transmitted through gears 80! and 802 and shaftsI03 and 806 from the above-mentioned clockwork.

Rotation of the wheel brings one of the pins 162 to bear on arm 480 andforces it to the right, thereby raising weighted member "0 again to theposition shown in Figure and resetting arm 0 on detent 44. As arm 430 isforced down, screw 100 falls, thus raising the opposite end of detent500 which engages the next tooth of the escape wheel and arrests itsrotation.

From this description it will be seen that on each full swing of thependulum, its bob receives an impulse from member ill, and escape wheel160 rotates one third or a turn, at the same time resetting the impulsemember. Since the pendulum is a seconds pendulum, this cycle occursevery two seconds and wheel 160 completes a rotation every six seconds.Accordingly the hands of the clockwork referred to above, which advancesix seconds with each revolution of wheel I60, indicate correct timeintervals.

The banking eilfect of pin 502 through detent I" and screw 100 on arm430 operates to lessen or prevent an impulse being imparted by member l0to anvil II in case the pendulum is momentarily swinging too wide sothat its angular velocity at the center of its swing is greater thannormal. This absence of or reduction in the impulse soon reduces theamplitude of the pendulum swing. On the other hand if the pendulum isnot swinging wide enough, the angular velocity of the bob is less at thecenter of the swing, and member 0 strikes anvil Ii slightly earlier inthe swing; this lengthens the duration of the impulse and increases theamplitude of the pendulum. Furthermore the faster the bob moves the lessenergy, and the slower it moves the more energy it absorbs from theimpulse member, which always falls at a constant rate. These actions aresimilar to those described in connection with the first embodiment andsimilarly tend to keep the arc of swing of the pendulum constant.

Another embodiment of my invention is illustrated diagrammatically inFigures 13 and 14. In this embodiment the pendulum is entirely free ofmechanical contact with the maintaining gear except for the nearlyinstantaneous tap of the imi2 pulse arm- Ill every two seconds on anvilI at the exact center of the pendulum swing.

The lower end of rod I I is provided with a lightweight opaque screenpierced by a slot "I. The screen intercepts light beam 903 from lamp "2which is focussed on three photoelectric cells 8, III! and I. As thependulum swings. however. slot "I permits beam "3 momentarily toilluminate the three photoelectric cells in turn. Consider a swing fromleft to right. Cell Ill is first energized by the beam; current passesthrough it and is amplified by amplifier "1, which may be of anysuitable commercially available type and is powered by current source"8; current passes through lead electromagnet coil Ill and return leadill. The coil Sill is part of a relatively slow-acting relay and when itis energized the magnet attracts pivoted armature Ill, causing it toclose the gap between its end and spring contact SIB. Owing to the slowaction of this relay, this gap remains closed while slot Ill illuminatescell a fraction of asecond later, causing current to pass through leadIll, electromagnet coil 8, lead lit, contact SIB, armature III, andreturn lead Ill. Magnet 9 attracts armature I" forming upper radial armof detent 9 pivoted at 0. This releases detent arm 8", integral withgravity-loaded impulse arm llll and return cam I", pivoted at 820, sothat impulse member falls and arm llll strikes anvil 4|, therebymaintaining the swing of the pendulum as described in connection withfirst-disclosed embodiment; in the present embodiment also banking screw6| functions, by contact with arm "I, to limit drop of impulse memberand thus keep the swings of pendulum II, II substantially constant.Positions of slot "I, lamp III and cell 805 are so adjusted that theimpulse occurs at the center of the pendulum swing.

As the swing of the pendulum continues, relay Ill-llB-Sli opens, cells"I and "I are darkened and detent 8 is returned to its original positionby a spring not shown.

Finally slot "I illuminates cell "I, which is so located that thisoccurs at the extreme right of the pendulum swing. Current then flowsthrough lead 9", electromagnet coil H and return lead Oil. Energizingcoil II causes magnet Ill to attract armature 13, thus rockingassociated reset lever pivoted at 14 and resetting detent arm 830 ondetent 9 by contact of stud 18 with reset cam I80.

On the return swing, when cell It! is illuminated, no current passesthrough magnet coil 9, since gap between armature m and contact ill isopen. Accordingly impulse member is released only on left-to-rightswings of the pendulum.

The counting mechanism associated with a pendulum of this type may beoperated in numerous ways, for example by a circuit I0! and II! inparallel with coil 6, or by an independent circuit and photoelectriccell.

A pendulum of this type absorbs only sufficient energy to overcome thefriction of passage through air and of the flexing of its suspensionsprings and gives up no appreciable energy in releasing the impulsemechanism; it is advantageously operated in a constant-temperature andconstant-pressure container or case.

It will be seen that in all the embodiments of my invention describedabove an isochronously oscillating member is kept oscillating by almostinstantaneous impulses imparted to it substantially at the mid point ofits excursions by an impulse member whose impulse strokes are banked orlimited by a fixed stop so positioned that abnormally wide excursions ofthe oscillating member partly or entirely escape the normal impact ofthe impulse member. In this way abnormally wide oscillations quicklydiminish to normal amplitude. Abnormally short excursions of theoscillating member are increased by reason of the resulting longer timeof contact of the impulse member with the oscillating member;furthermore I prefer to reinforce this action by providing a slightlymore energetic impulse than is required to maintain normal oscillations,the excess energy being absorbed by impact of the impulse member withthe fixed stop.

A counting or time-indicating mechanism is preferably associated withthe impulse member in such a way that its indications are controlledsolely by the action of the impulse member but in strict synchronismwith the oscillating member. Thus no. energy is absorbed by the countingmechanism from the oscillating member nor does the former react on thelatter. Accordingly the isochronism of the oscillating member is notdisturbed by the functioning of the counting or time-indicatingmechanism.

While it is desirable from the viewpoint of consistent timekeeping tolimit any necessary in terference with an isochronously oscillatingmembere. g., release of-impulse member and impulse-to positions as closeas possible to the mid point of the oscillations, some deviation fromthis practise is possible for many purposes without serious practicaldisadvantage. The chief requisite is to keep the oscillating member freeof interference at the-ends of its oscillations, but it is furtherpreferable to confine such interference to the central portion of theoscillations. For example, in the embodiments shown in Figures 3 and 9adjustments may be made so that the impulse occurs at substantially themid point of the pendulum swing and the release occurs a necessaryfraction of the are before the impulse, or so that the release andimpulse occur on opposite sides of the mid point of the swing. For manypurposes good results are had if the impulse occurs not more than A thehalf swing away from the mid point; in the claims I have used the phrase"at approximately the mid point in this sense.

I claim:

1. A clock comprising an isochronously oscillating pendulum having abob, an anvil fixedly associated with the pendulum at a point not remotefrom the bob and having an impact face normal to the path of travel ofthe bob, an impulse member adapted to deliver an impact of onlysubstantially instantaneous duration to the impact face of said anvil atapproximately the mid point of the oscillations of the pendulum when theimpulse member is released from a biased position, a detent adapted toretain the impulse member in its biased position, a trigger on thedetent adapted to release the impulse member by displacement of thedetent when moved in one direction but free to move in the otherdirection without action on the detent, a trigger-pull mounted on thependulum adapted to engage the trigger, a banking stop adapted to limitthe impulse stroke of the impulse member in fixed relation to theoscillations of the pendulum, a powered reset means adapted whenoperated to contact the impulse member in its released position andreset it to its biased position, means associated with the impulsemember to cause the reset means to operate after each release of theimpulse member. and powered time-indicating means controlled by theaction of the impulse member to indicate time in synchronism with butwithout reaction on the pendulum.

2. A clock as defined in claim 1 in which the reset means and thetime-indicating means are elcctromagnetically powered, a source ofelectric current, leads connecting the current source in circuit withthe reset means and the time-indicating means, a common switchcontrolling passage of current to the reset means and time-indicatingmeans, said switch being responsive to the action of the impulse member.

3. A clock as defined in claim 2 in which the reset means and thetime-indicating means are electromagnetically powered and controlled bya common oscillatory mercury switch having an operating angleindependent of the angle of swing of the pendulum, said switch beingpivotally mounted on fixed bearings and operated by a pivoted armresponsive to the action of the impulse member.

4. A clock as defined in claim 2 in which the impulse member is anoscillating member and the reset means and time-indicating means areelectromagnetically powered and controlled by a common mercury switchmounted on and oscillating with the impulse member.

5. A clock as defined in claim 1 in which the reset means comprises anescape wheel having an element adapted to engage the impulse member whenreleased from its biased position and on rotation of the escape wheel toreset the impulse member to its biased position, and in which mechanicaloperating means connects said escape wheel with the time indicatingmeans, whereby rotation of the escape wheel is accompanied by actuationof the time-indicating means.

6. A program clock comprising an isochronously oscillating pendulum, animpulse member adapted to deliver an impact of only substantiallyinstantaneous duration to a point on on near the bob of said pendulum atapproximately the mid point of its oscillations when the impulse memberis released from a biased position, a detent adapted to retain theimpulse member in its biased position, a trigger on the detent adaptedto release the impulse member by displacement' of the detent when movedin one direction but free to move in the other direction without actionon the detent, a trigger-pull mounted on the pendulum adapted to engagethe trigger, a banking stop adapted to limit the impulse stroke of theimpulse member in fixed relation to the oscillations of the pendulum, apowered reset means adapted when operated to contact the impulsemember'in its released position and reset it to its biased position,means associated with the impulse member to cause the reset means tooperate after each release of the impulse member, poweredtime-indicating means controlled by action of the impulse member toindicate time in synchronism with but without reaction on the pendulum,said time-indicating means having at least one arbor rotating in timedrelation to but without reaction on the oscillations of the pendulum,and signal means actuated by rotation of the arbor.

7. A combination comprising a pendulum having a bob, means formaintaining oscillations of the pendulum solely by delivering successivesubstantially instantaneous impacts to an impact face of the bob at anintermediate point not remote from the mid point of its oscillations,said impact face being a plane surface normal to the path of travel ofthe bob, means responsive to travel of said pendulum at an intermediatepoint in its oscillations for effecting operation of said impactdelivering means, whereby said pendulum is free of interference at theends of its oscillations, and means responsive to movement of saidimpact-delivering means for restoring said impact-delivering means tocondition for delivering another impact to said bob during a subsequentoscillation of said pendulum.

8. The combination comprising a pendulum having a bob adapted to swingin a predetermined path, an impact-delivering member pivoted to swing inanother path, the path of said pendulum bob at an intermediate point ofits swing intersecting the path of said member, means responsive tomovement of said pendulum at an intermediate point of its swing foreffecting actuation of said member to deliver an impact of onlysubstantially instantaneous duration to said bob at an intermediatepoint of its swing and means responsive to movement of said member forrestoring it to a position out of the path of said bob for deliveringanother impact to said bob.

9. A clock comprising a pendulum with 9. bob, a pivoted impulse memberadapted to deliver from a biased position an impact of onlysubstantially instantaneous duration to said bob at approximately themid point of its swings, a movable detent member including a triggeradapted to retain said impulse member in its biased position, saidtrigger being movably mounted on said detent and adapted only whenpulled in one direction to move said detent to release said impulsemember, a trigger-pull on said pendulum adapted to move said trigger inits operative direction at a point in the pendulum swing not furtherremoved from the center of swing than about the half swing, a mercuryswitch mounted to swing with the impulse member and close a circuit whenthe member is in its released position, a banking stop positioned tolimit the impact movement of the 'impulse member in fixed relation tothe pendulum swings, a pivoted reset lever adapted when operated toreset the impuse member to its biased position, inertia weights on saidreset lever balanced to urge said lever to a non-operative position, anarmature on said reset lever, an electromagnet adapted when energized toattract said armature and thereby bring the reset lever into operativeposition to reset said impulse member to its biased position, anelectromagnetically operated time-indicating means, a source of electriccurrent, and electric leads connecting said source with said mercuryswitch, said electromagnet and said time-indicating means, whereby aftereach operation of said impulse member it is reset to its biased positionand the time-indicating means operates in synchronism with but withoutreacting on the pendulum.

10. A clock comprising a pendulum with a bob, a pivoted impulse memberadapted to deliver from the biased position an impact of onlysubstantially instantaneous duration to said bob at approximately themid point of its swings, a movable detent member including a triggeradapted to retain said impulse member in its biased position, saidtrigger being movably mounted on said detent and adapted only whenpulled in one direction to move said detent to release said impulsemember, a trigger-pull on said pendulum adapted to move said trigger inits operative direction at a point' in the pendulum swing not furtherremoved from the center of swing than about A the half swing, a bankingstop positioned to limit the impact movement of the impulse member infixed relation to the pendulum swings, a pivoted reset lever adaptedwhen operated to reset the impulse member to its biased position,biasing means associated with said reset lever to urge it to anoperative position, a retaining means on said reset lever, a detentlever adapted to engage the retaining means on the reset lever to holdthe reset lever in non-operative biased position, means on the impulsemember adapted when the impulse member is in released position todisengage said detent lever from said retaining means thereby releasingthe reset lever to move to an operative position and reset the impulsemember to a biased position, an armature on the reset lever adapted whenattracted to move the reset lever to a biased position in which it isretained by the detent lever, an electromagnet adapted when energized toattract said armature thereby moving it to its biased position, anelectric switch, an arm on said reset lever adapted to open said switchwhen the reset lever is in biased position and close it when the resetlever is in operative position, a source of efectric current, anelectromagnetically operated time-indicating means and electric leadsconnecting said source with said switch, said electromagnet and saidtime-indicating means, whereby after each operation of said impulsemember it is reset to its biased position and the time-indicating meansoperates in synchronism with but without reacting on the pendulum.

11. A clock comprising a pendulum with 8. bob, a pivoted impulse memberadapted to deliver from a biased position an impact of onlysubstantially instantaneous duration to said bob at approximately themid point of its swings, a movable detent member including a triggeradapted to retan said impulse member in its biased position, saidtrigger being movably mounted on said detent and adapted only when puledin one direction to move said detent to release said impulse member, atrigger-pull on said pendulum adapted to move said trigger in itsoperative direction at a point intermediate the ends of the swings ofthe pendulum, an escape wheel provided with detaining and reset means,the reset means being adapted on rotation of the wheel to engage theimpulse member in its released position and move it to its biasedposition, a detent lever adapted in its equilibrium position to engagesaid detaining means and prevent rotation 'of the escape wheel andadapted to be rium position by movement of the impulse member to itsreleased position thereby permitting rotation of the escape wheel,banking means adapted to limit movement of the detent lever and theimpulse member, powered time-indicating means, and mechanical meansconnecting the time-indicating means with the escape wheel andreversibly applying torque to the latter, whereby the poweredtime-indicating means furnishes energy for maintaining the oscillationsof the pendulum and is controlled in its indications to synchronize withbut not react on the oscillations of the pendulum.

12. A combination comprising an isochronously oscillating pendulum,impulse means adapted to deliver an impact of only substantiallyinstantaneous duration to a point not remote from the bob of thependulum at an intermediate point in its oscillations, means responsiveto oscillations of the pendulum for effecting operation of the impulsemeans without reaction on the pendulum at the ends of its oscillations,and means for removed from its equilibstoring the impulse means tocondition for delivering another impact to the pendulum.

13. A clock comprising an isochronously oscillating pendulum,maintaining gear, and timewhich a banking stop is provided to engage theimpulse member at the instant of impact to cause the impact to occur ata desired intermediate point in the swing of the pendulum and topreindicating means; said maintaining gear comprisvent prolongation ofthe contact between the iming an impulse member adapted to maintain thepulse member and the bob. oscillations of said pendulum solely bydelivering 16. In combination, a pendulum having a bob, aseries of timedsubstantially instantaneous horia bell crank lever pivoted adjacent thepath of zontally directed impacts to the bob of the said bob, one arm ofsaid bell crank lever being pendulum at an intermediate point in itsosciladapted to impart instantaneous impacts to said lations when theimpulse member is released from bob, a detent member including a triggerengaga biased position, a detent adapted to retain the ing the other armof said bell crank lever to impulse member in its biased position andperiodimaintain the impact arm out of the path of movecally to releaseit from its biased position in rement of the bob during movement of thependu-. sponse to the travel of the pendulum, a banklum in onedirection, said trigger being movably ing stop adapted to limit theimpulse stroke of the mounted on said detent, a trigger pull on saidimpulse member in fixed relation to the oscillapendulum, said triggerpull engaging said trigger tions of the pendulum, and powered resetmeans when the pendulum is moving in said one direcfor restoring theimpulse member to its biase tion without releasing said detent from saidother position after each impact, said maintaining gear :0 arm but uponmovement of said pendulum in being without reaction on the pendulum atthe the reverse direction, said trigger pull operating ends of itsoscillations; and said time-indicating said trigger to release saiddetent from said other means comprising counting means responsive to armto impart an instantaneous impact to said the action of said maintaininggear but without pe u b y the impact arm 0f Said l ti on said impulsemember or said crank lever, and means for restoring the bell pendulum.crank lever to its original position with the im- 14. In combination, apendulum having a bob, pact arm out of the path of movement of the animpulse member having an impact portion bob. and a detent portion, adetent member including MARSTON LOVELL HAMLIN. a trigger engaging saiddetent portion to maintain the impact portion out of the path of theREFERENCES CITED pendulum during movement of the pendulum in 7 onedirection, said trigger being movably mounted i ififizf gf are or recordm the on said detent and adapted to engage a portion of the pendulumduring its movement in said di-' 85 UNITED STATES PATENTS rectionwithout efieeting release of said detent N b r Name Date portion by saiddetent but adapted upon move- 205,303 Pratt July 9, 1878 ment of theendulum in the reverse direction 1,043,917 Fery Nov. 12, 1912 to engagesaid portion of the pendulum to efiect 1,564,303 Warren Dec. 8, 1925refease of said detent portion by said detent to 1,743,231 Packard Jan.14, 1930 cause said impact portion to impart a substan- 2,033,899 PooleMar. 10, 1936 tially instantaneous impact to the pendulum bob, and meansfor restoring the impulse member FOREIGN PATENTS and the detent to aposition such that said impact Number Country Date portion is maintainedout 01' the path or said 919 Great Britain Jan. 14, 1908 P m- 160,204Great Britain Mar. 17, 1921 15. A combination as defined in claim 14, in233,828 Great Britain May 21, 1925 Certificate of Correction Patent No.2,482,061

September 13, 1949 MARSTON LOVELL HAMLIN It is hereby certified thaterrors appear in the printed specification of the above numbered patentrequiring correction as follows:

Column 3, line 18, for the words an d dial? read the dial; column 4,line 22, for

lumn 7, line '61, for "com "plane read plate; line 36, for plante readlate; 00 read cam; column 14, line 42, for on near rea or near;

and that the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Oflice. Signed and sealed this 13th day of June, A. D. 1950.

THOMAS i3" ME RPHY 5i eats up"; i ommzssm

